The aim of the proposal is to study the contribution of cardiac and renal receptors to the control of body salt and water homeostasis in the normal primate and in the primate with heart failure. The initial studies will involve characterization of atrial receptors in terms of their appropriate stimulus and the extent to which there may be a feedback control. Subsequently, the renal responses to stimulation of atrial receptors will be determined. Finally renal receptors will be characterized in normal animals.